Patent Literature 1 describes a device which detects a curving amount of a linear body 9006. The device in Patent Literature 1 has, in the linear body 9006, a unit which obtains a collapsed condition of the linear body 9006. Therefore, its manufacturing cost becomes higher.
In addition, Patent Literature 1 describes insertion length detection means which measures an insertion length of the linear body 9006. As shown in FIG. 29, marks 9021 are provided at predetermined intervals on a surface of the linear body 9006 in Patent Literature 1. A sensor 9022 counts the number of passed marks 9021 to acquire the length of the linear body 9006 inserted into a body of a patient based on the number of passed marks 9021. The insertion length detection means measures the length of the linear body 9006 which has passed before the sensor 9022, but does not measure a distance between two points of the linear body 9006.